This invention is directed to the use of particular pseudo double salts of alkyl orthophosphates as gelling agents for hydrocarbons and to a method for gelling liquid hydrocarbons. More particularly, the invention is directed to pseudo double salts of alkyl orthosphosphates prepared by first reacting a mixture of alkanols and/or alkenols with phosphorus pentoxide then reacting the alkyl orthosphosphate with from 25 to 75% of a stoichiometric equivalent of a basic aluminum compound, followed by neutralization with a second base. These pseudo double salts are efficient gelling agents for hydrocarbons and effect a reduction in fluid friction in high shear flow of hydrocarbons.
Prior to the instant invention, there were a variety of aluminum salts of specific orthophosphates which were used as gelling agents in the preparation of hydrocarbon gels for use in oil well cracking and for other end uses. Examples of dialkyl monohydrogen orthophosphates used as gelling agents in the aluminum form may be found in U.S. Pat. Nos. 3,494,949, 3,505,374 and 3,575,859 issued to Monroe. In U.S. Pat. No. 3,757,864, stoichiometric aluminum salts of orthophosphates are disclosed as fluid friction reducing agents and as gelling agents for hydrocarbons. Related salts of acid hydrocarbyl orthophosphates of titanium, zirconium and hafnium may be found in U.S. Pat. Nos. 3,338,935 issued to Kerschner and 3,334,978 issued to Revurkas. The latter mentioned salts of hydrocarbyl compounds are used as fuel additives rather than as gelling agents.
The aforementioned aluminum salts of dialkyl monohydrogen orthosphosphates have exhibited certain disadvantages as gelling agents. One of the major disadvantages has been that these agents are difficult to dissolve and fail to disperse throughout the hydrocarbon and a uniform gel difficulty obtained. The inability to disperse the gelling agent caused the gel to form in a sequestered portion of the liquid hydrocarbon solution with no effect on the remaining hydrocarbon composition. In order to completely disperse the gelling agent, it was normally necessary to heat the hydrocarbon solution to a sufficiently high temperature to disperse the agent throughout and then allow the composition to cool to that point where a gel would form.
The control of the amount of gelation was also somewhat lacking in most prior art systems because there was no efficient way to cause a gel to form at the proper point required for a given end use. Thus, the composition would form a gel only with the total gelling agent present and control over the physical properties of the completed gel was somewhat lacking.